Direct Imaging of Exoplanets: Prospects for Comparative Exoplanetology

Beth Biller (IfA, University of Hawaii)

Direct detection, and direct spectroscopy in particular, has the potential of ushering in the era of comparative exoplanetology -- where we will be able to 1) fully map out the architecture of typical planetary systems and 2) study the physical properties of exoplanets in depth. Direct detection is complementary to other methods of planet detection such as the radial velocity or transit techniques. In addition, by directly detecting photons from planets, we attain critical information (luminosity, colors) about planets. However, numerous technical issues limit direct detection today to the brightest, youngest, most massive planets. I discuss the current crop of methods and surveys for direct imaging of planets including the Gemini Deep Planet Survey, the Simultaneous Differential Imaging survey at the VLT and MMT, and the NICMOS planet survey with HST. While no planets were found in these surveys, they set important constraints on the distribution of outer extrasolar planets -- specifically, the fraction of stars with planets with semi-major axis from 20 to 100 AU, and mass > M_Jup is 20% or less. I will also discuss future prospects for direct detection, including the NICI science campaign at Gemini South, starting in fall 2007. Currently, direct detection is limited to the youngest, brightest objects -- I will discuss the technical advances necessary to directly image earthlike planets.